Method for terminal resending data in wireless communication system, and communication device using same

ABSTRACT

Provided are a method for a terminal resending data in a wireless communication system, and a communication device using same. The method comprises: receiving downlink control information (DCI) from a network; and resending data on the basis of the DCI, wherein the DCI includes an acknowledgement/not-acknowledgement (ACK/NACK) field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2018/000370, filed on Jan. 8, 2018,which claims the benefit of U.S. Provisional Application No. 62/443,649filed on Jan. 7, 2017, the contents of which are all hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention related to wireless communication and, mostparticularly, to a method for a terminal resending data in a wirelesscommunication system, and a communication device using the same.

Related Art

As more communication devices utilize greater communication capacity,there is a need for improved mobile broadband communication overexisting radio access technology. Also, massive machine typecommunications (MTC), which provides various services by connecting manydevices and objects, is one of the major issues to be considered in thenext generation communication.

In addition, communication system design considering reliability/latencysensitive service/UE is being discussed. The introduction of nextgeneration radio access technology considering enhanced mobile broadbandcommunication (eMBB), massive MTC (mMTC), ultrareliable and low latencycommunication (URLLC) is discussed. This new technology may be callednew radio access technology (new RAT or NR) in the present disclosurefor convenience.

Meanwhile, retransmission of data through a hybrid automatic repeatrequest (HARQ) process may also be performed in the NR. However, in theNR, by defining a channel that spreads in system bandwidth units,discussions are being made on a more efficient usage method for usingsymbols being consumed. And, accordingly, discussions are also beingmade on a method for performing an HARQ process without adopting aphysical HARQ indicator channel (PHICH) in the related art LTE.

Accordingly, the present invention uses downlink control information(DCI) as a retransmission indicator so as to provide a method performedby a terminal (or user equipment (UE)) resending (or retransmitting)data.

SUMMARY OF THE INVENTION Technical Objects

A technical object that is to be achieved by the present invention is toprovide a method for a terminal resending data in a wirelesscommunication system, and a communication device using the same.

Technical Solutions

According to an embodiment of the present invention, provided is amethod for retransmitting data of a user equipment (UE) in a wirelesscommunication system. The method is comprising receiving downlinkcontrol information (DCI) from a network, and retransmitting data basedon the DCI, wherein the DCI includes anacknowledgement/not-acknowledgement (ACK/NACK) field.

Here, the retransmission may be a non-adaptive retransmission.

Here, the DCI may indicate retransmission per hybrid automatic repeatrequest process identifier (HARQ process ID).

Here, the DCI may indicate retransmission per subframe within a subframewindow.

Here, in case a counter field informing a scheduling index within theuplink (UL) grant is defined, the DCI may signal a last counter value.

Here, the counter value may be initialized when the DCI is received.

Here, in case a polling on/off field is defined within the UL grant,and, when a polling on UL grant is received in an N^(th) subframe, an ULgrant being the indication target of the DCI that is received after atime point of the N^(th) subframe may correspond to an uplink grant thatis received during a duration starting from a reception point of anearest polling on uplink grant before the N^(th) subframe to an(N−1)^(th) subframe.

Here, the DCI may correspond to a UE-specific DCI or a UE-common DCI.

Here, the DCI may include at least any one of a non-adaptiveretransmission on/off field, a non-adaptive retransmission timing field,a redundancy version (RV) field, and an aperiodic channel stateinformation (CSI) transmission request field.

Here, a radio network temporary identifier (RNTI) value being related toa detection of the DCI may be independently signaled.

Here, a transmission-related parameter within a search space for the DCImay be predetermined.

Here, in case the UE receives both the DCI and uplink grant for a sameHARQ process ID, retransmission may be performed in accordance with theuplink grant.

Here, an HARQ ACK transmission timing field may be configured per HARQprocess ID within the DCI.

Here, an acknowledgement/not-acknowledgement resource indicator (ARI)field may be configured per HARQ process ID within the DCI.

According to another embodiment of the present invention, provided is acommunication device comprising a radio frequency (RF) unit transmittingand receiving radio signals and a processor being operatively connectedto the RF unit. The processor is configured to receive downlink controlinformation (DCI) from a network, and to retransmit data based on theDCI, wherein the DCI includes an acknowledgement/not-acknowledgement(ACK/NACK) field.

Effects of the Invention

According to the present invention, when the terminal (or user equipment(UE)) performs data retransmission (or resends data), by using DCI as aretransmission indicator, a more efficient retransmission may beperformed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a wireless communication system according tosome implementations of the present disclosure.

FIG. 2 is a diagram showing an example of a wireless protocolarchitecture for a user plane.

FIG. 3 is a diagram showing an example of a wireless protocolarchitecture for a control plane.

FIG. 4 shows the structure of an uplink subframe in 3GPP LTE.

FIG. 5 shows the structure of a downlink subframe in 3GPP LTE.

FIG. 6 shows an example of a method of performing an uplink HARQ in 3GPPLTE.

FIG. 7 illustrates a system structure of a next generation radio accessnetwork (NG-RAN) according to some implementations of the presentdisclosure.

FIG. 8 illustrates an example of a functional division that may beimplemented between an NG-RAN and a 5GC.

FIG. 9 illustrates an example of a frame structure according to someimplementations of the present disclosure.

FIG. 10 shows an example of a multiplexing scheme within a single slotin the NR.

FIG. 11 is a flow chart showing a method for retransmitting data of a UEaccording to an exemplary embodiment of the present invention.

FIG. 12 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

FIG. 13 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

FIG. 14 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

FIG. 15 shows a detailed example of applying the method of FIG. 11.

FIG. 16 is a block diagram illustrating a communication device in whichembodiments of the present invention are implemented.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows an example of a wireless communication system according tosome implementations of the present disclosure. In some scenarios, thewireless communication system may be compatible with one or moretechnical standards. For example, in some scenarios, the wirelesscommunication system in FIG. 1 may be referred to as an Evolved-UMTSTerrestrial Radio Access Network (E-UTRAN) or a Long Term Evolution(LTE)/LTE-A system.

In this example, the E-UTRAN includes at least one base station (BS) 20which provides a control plane and a user plane to a user equipment (UE)10. The UE 10 may be fixed or mobile, and may be referred to by anotherterminology, such as a mobile station (MS), a user terminal (UT), asubscriber station (SS), a mobile terminal (MT), a wireless device, etc.The BS 20 is generally a fixed station that communicates with the UE 10and may be referred to by another terminology, such as an evolved node-B(eNB), a base transceiver system (BTS), an access point, etc.

The BSs 20 may be interconnected by an interface, such as an X2interface. The BSs 20 may also be connected by an interface, such as anS1 interface, to an evolved packet core (EPC) 30. For example, in someimplementations, the BSs 20 may be connected to a mobility managemententity (MME) through an interface, such as an S1-MME interface, and to aserving gateway (S-GW) through another interface, such as an S1-Uinterface.

In some implementations, the EPC 30 includes an MME, an S-GW, and apacket data network-gateway (P-GW). The MME has access information ofthe UE or capability information of the UE, and such information isgenerally used for mobility management of the UE. The S-GW is a gatewayhaving an E-UTRAN as an end point. The P-GW is a gateway having a PDN asan end point.

A radio interface protocol may be implemented between the UE and thenetwork. Layers of the radio interface protocol between the UE and thenetwork may be classified into a first layer (L1), a second layer (L2),and a third layer (L3), for example, based on the lower three layers ofthe open system interconnection (OSI) model. Among these, a physical(PHY) layer belonging to the first layer provides an informationtransfer service by using a physical channel, and a radio resourcecontrol (RRC) layer belonging to the third layer serves to control aradio resource between the UE and the network. In some implementations,the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing an example of a wireless protocolarchitecture for a user plane. FIG. 3 is a diagram showing an example ofa wireless protocol architecture for a control plane. The user plane isa protocol stack for user data transmission. The control plane is aprotocol stack for control signal transmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer, which is an upperlayer of the PHY layer, through a transport channel Data is transferredbetween the MAC layer and the PHY layer through the transport channel.The transport channel may be classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is transferred between different PHY layers, for example, betweenPHY layers of a transmitter and a receiver, through a physical channel.The physical channel may be modulated according to a suitable modulationtechniques, e.g., Orthogonal Frequency Division Multiplexing (OFDM),using time and frequency as radio resources.

The functions of the MAC layer include, for example, mapping between alogical channel and a transport channel and multiplexing anddemultiplexing to a transport block that is provided through a physicalchannel on the transport channel of a MAC Service Data Unit (SDU) thatbelongs to a logical channel The MAC layer provides service to a RadioLink Control (RLC) layer through the logical channel

The functions of the RLC layer include, for example, concatenation,segmentation, and reassembly of an RLC SDU. In some scenarios, toguarantee various types of Quality of Service (QoS) required by a RadioBearer (RB), the RLC layer provides three types of operation modes:Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode(AM). Among these, in some implementations, AM RLC provides errorcorrection through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane, according to someimplementations. The RRC layer is related to, for example, theconfiguration, reconfiguration, and release of radio bearers, and isresponsible for control of logical channels, transport channels, and PHYchannels. An RB is a logical route that is provided by the first layer(PHY layer) and the second layers (MAC layer, the RLC layer, and thePDCP layer) in order to transfer data between UE and a network.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes, for example, the transfer of user data and headercompression and ciphering. The function of the PDCP layer on the userplane further includes, for example, the transfer andencryption/integrity protection of control plane data.

The process of configuring an RB may include defining thecharacteristics of a wireless protocol layer and channels in order toprovide specific service and configuring each detailed parameter andoperating method. An RB may be, for example, a Signaling RB (SRB) or aData RB (DRB). The SRB is used as a passage through which an RRC messageis transmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If an RRC connection is established between the RRC layer of UE and theRRC layer of an E-UTRAN, then the UE is referred to as being in the “RRCconnected state.” If not, the UE is referred to as being in the “RRCidle state.”

A downlink transport channel through which data is transmitted from anetwork to UE includes, for example, a broadcast channel (BCH) throughwhich system information is transmitted and a downlink shared channel(SCH) through which user traffic or control messages are transmitted.Traffic or a control message for downlink multicast or broadcast servicemay be transmitted through the downlink SCH, or may be transmittedthrough an additional downlink multicast channel (MCH). In someimplementations, an uplink transport channel through which data istransmitted from UE to a network includes, for example, a random accesschannel (RACH) through which an initial control message is transmittedand an uplink shared channel (SCH) through which user traffic or controlmessages are transmitted.

Logical channels that are implemented over the transport channel, andthat are mapped to the transport channel, include, for example, abroadcast control channel (BCCH), a paging control channel (PCCH), acommon control channel (CCCH), a multicast control channel (MCCH), and amulticast traffic channel (MTCH).

The physical channel includes several symbols (e.g., OFDM symbols) inthe time domain and several subcarriers in the frequency domain. Onesubframe includes a plurality of OFDM symbols in the time domain. An RBis a unit of resource allocation for the communication system, andincludes a plurality of OFDM symbols in the time domain and a pluralityof subcarriers in the frequency domain. In some implementations, foreach subframe, specific subcarriers of specific OFDM symbols (e.g., thefirst OFDM symbol) of the corresponding subframe may be allocated for aphysical downlink control channel (PDCCH), e.g., an L1/L2 controlchannel A Transmission Time Interval (TTI) is a unit of time for asingle subframe transmission.

FIG. 4 shows the structure of an uplink subframe in 3GPP LTE.

The uplink subframe can be divided into a control region and a dataregion in a frequency domain Physical uplink control channels (PUCCHs)on which uplink control information is transmitted are allocated to thecontrol region. Physical uplink shared channels (PUSCHs) through whichdata is transmitted are allocated to the data region. A terminal maysend or may not send a PUCCH and a PUSCH at the same time depending on aconfiguration.

A PUCCH for one terminal is allocated as an RB pair in a subframe. RBsbelonging to the RB pair occupy different subcarriers in a first slotand a second slot. A frequency occupied by RBs that belong to an RB pairallocated to a PUCCH is changed on the basis of a slot boundary. This iscalled that the RB pair allocated to the PUCCH has been frequency-hoppedin the slot boundary. A terminal can obtain a frequency diversity gainby sending uplink control information through different subcarriers overtime.

Uplink control information transmitted on a PUCCH includes ACK/NACK,Channel State Information (CSI) indicative of a downlink channel state,a Scheduling Request (SR), that is, an uplink radio resource allocationrequest, etc. The CSI includes a Precoding Matrix Index (PMI) indicativeof a precoding matrix, a Rank Indicator (RI) indicative of a rank valuethat is preferred by UE, a Channel Quality Indicator (CQI) indicative ofa channel state, etc.

A PUSCH is mapped to an uplink shared channel (UL-SCH), that is, atransport channel. Uplink data transmitted on the PUSCH can be atransmission block, that is, a data block for an UL-SCH that istransmitted during a TTI. The transmission block can be userinformation. Alternatively, the uplink data can be multiplexed data. Themultiplexed data can be obtained by multiplexing the transmission blockfor the UL-SCH and control information. For example, control informationmultiplexed with data can include a CQI, a PMI, ACK/NACK, an RI, etc.Alternatively, the uplink data may include only control information.

FIG. 5 shows the structure of a downlink subframe in 3GPP LTE.

The downlink subframe includes two slots in a time domain, and each ofthe slots includes 7 OFDM symbols in a normal CP. A maximum of former 3OFDM symbols (i.e., a maximum of 4 OFDM symbols for a 1.4 MHz bandwidth)in the first slot within the downlink subframe corresponds to a controlregion to which control channels are allocated, and the remaining OFDMsymbols correspond to a data region to which Physical Downlink SharedChannels (PDSCHs) are allocated. The PDSCH means a channel on which datais transmitted from a BS or a node to UE.

Control channels transmitted in the control region include a physicalcontrol format indicator channel (PCFICH), a physical hybrid-ARQindicator channel (PHICH), and a physical downlink control channel(PDCCH).

A PCFICH transmitted in the first OFDM symbol of the subframe carries aControl Format Indicator (CFI), that is, information about the number ofOFDM symbols (i.e., the size of the control region) that is used to sendcontrol channels within the subframe. A terminal first receives a CFI ona PCFICH and then decodes a PDCCH. Unlike a PDCCH, a PCFICH does not useblind decoding, and the PCFICH is transmitted through the fixed PCFICHresource of a subframe.

A PHICH carries an acknowledgement (ACK)/not-acknowledgement (NACK)signal for an uplink Hybrid Automatic Repeat request (HARQ). An ACK/NACKsignal for uplink data transmitted by UE is transmitted through a PHICH.The PHICH is described in detail later.

A PDCCH is a control channel on which Downlink Control Information (DCI)is transmitted. The DCI can include the allocation of PDSCH resources(also called downlink grant (DL grant)), the allocation of physicaluplink shared channel (PUSCH) resources (also called an uplink grant (ULgrant)), a set of transmit power control commands for individual UEswithin a specific terminal group and/or the activation of a Voice overInternet Protocol (VoIP).

FIG. 6 shows an example of a method of performing an uplink HARQ in 3GPPLTE.

A terminal receives the allocation of initial uplink resources on aPDCCH 310 in an n^(th) subframe from a BS.

The terminal sends uplink data, more particularly, an uplinktransmission block on a PUSCH 320 in an (n+4)^(th) subframe using theallocation of the initial uplink resources.

The BS sends an ACK/NACK signal for the uplink transmission block on aPHICH 331 in an (n+8)^(th) subframe. The ACK/NACK signal indicates theconfirmation of the reception of the uplink transmission block, the ACKsignal indicates successful reception, and the NACK signal indicatesunsuccessful reception.

The terminal which has received the NACK signal sends a retransmissionblock on a PUSCH 340 in an (n+12)^(th) subframe.

The BS sends an ACK/NACK signal for the uplink transmission block on aPHICH 351 in an (n+16)^(th) subframe.

After initial transmission in the (n+4)^(th) subframe, theretransmission is performed in the (n+12)^(th) subframe. Accordingly, anHARQ is performed using 8 subframes as an HARQ cycle.

In 3GPP LTE, 8 HARQ processes can be performed. The HARQ processes areassigned indices from 0 to 7. The aforementioned example shows that anHARQ in an HARQ process index 4.

Hereinafter, new radio access technology (new RAT or NR) will bedescribed.

As more communication devices utilize greater communication capacity,there is a need for improved mobile broadband communication overexisting radio access technology. Also, massive machine typecommunications (MTC), which provides various services by connecting manydevices and objects, is one of the major issues to be considered in thenext generation communication. In addition, communication system designconsidering reliability/latency sensitive service/UE is being discussed.The introduction of next generation radio access technology consideringenhanced mobile broadband communication (eMBB), massive MTC (mMTC),ultrareliable and low latency communication (URLLC) is discussed. Thisnew technology may be called new radio access technology (new RAT or NR)in the present disclosure for convenience.

FIG. 7 illustrates a system structure of a next generation radio accessnetwork (NG-RAN) according to some implementations of the presentdisclosure.

Referring to the example of FIG. 7, the NG-RAN may include a gNB and/oran eNB that provides user plane and control plane protocol terminationto a terminal. The example of FIG. 7 illustrates the case of includingonly gNBs, but implementations are not limited thereto. The gNB and theeNB are connected by an interface, such as an Xn interface. The gNB andthe eNB are connected to a 5G core network (5GC) via an interface, suchas an NG interface. In some implementations, the gNB and the eNB areconnected to an access and mobility management function (AMF) via aninterface, such as an NG-C interface, and are connected to a user planefunction (UPF) via another interface, such as an NG-U interface.

FIG. 8 illustrates an example of a functional division that may beimplemented between an NG-RAN and a 5GC.

According to some implementations, the gNB may provide functions such asan inter-cell radio resource management (Inter Cell RRM), radio bearermanagement (RB control), connection mobility control, radio admissioncontrol, measurement configuration & provision, dynamic resourceallocation, and the like. The AMF may provide functions such as NASsecurity, idle state mobility handling, and so on. The UPF may providefunctions such as mobility anchoring, PDU processing, and the like. TheSMF may provide functions such as UE IP address assignment, PDU sessioncontrol, and so on.

FIG. 9 illustrates an example of a frame structure according to someimplementations of the present disclosure. This frame structure may, forexample, by compatible with new radio access technology.

In NR, a structure in which a control channel and a data channel aretime-division-multiplexed within one TTI, as shown in FIG. 9, may beimplemented as a frame structure. Such frame structure implementationscan, in some scenarios, help reduce latency.

In the example of FIG. 9, a shaded region represents a downlink controlregion and a black region represents an uplink control region. Theremaining region may be used for downlink (DL) data transmission oruplink (UL) data transmission. This structure is characterized in thatDL transmission and UL transmission are sequentially performed withinone subframe and thus DL data can be transmitted and UL ACK/NACK can bereceived within the subframe. Consequently, in some scenarios, a timeperiod from an occurrence of a data transmission error to a dataretransmission may be reduced, thereby reducing latency in datatransmission.

In this data and control time-division multiplexed (TDMed) subframestructure, a time gap may be implemented, for a base station and aterminal to switch from a transmission mode to a reception mode or fromthe reception mode to the transmission mode. To this end, some OFDMsymbols at a time when DL switches to UL may be set to a guard period(GP) in the self-contained subframe structure.

Meanwhile, the following techniques may be applied in association withan uplink of the NR.

<PUCCH Formats in the NR>

In NR, PUCCH formats may have the following characteristics.

A PUCCH may deliver uplink control information (UCI). Additionally,PUCCH formats may be differentiated from one another in accordance witha duration/payload size. For example, PUCCH formats may be categorizedas a “Short Duration Uplink Control Channel (SHD_PUCCH)” and a “LongDuration Uplink Control Channel (LGD_PUCCH)”. The SHD_PUCCH may bereferred to as a short PUCCH for simplicity, and, herein, format 0 (≤2bits) and format 2(>2 bits) may correspond to the short PUCCH. TheLGD_PUCCH may be referred to as a long PUCCH for simplicity, and,herein, format 1(≤2 bits), format 3(>2, [>N] bits), and format 4(>2,[≤N] bits) may correspond to the long PUCCH.

Meanwhile, a transmission diversity method for the PUCCH may not besupported in Rel-15. Additionally, synchronized physical uplink sharedchannel (PUSCH) and PUCCH transmission may not be supported in Rel-15.

Meanwhile, PUCCH formats in the NR may be defined as shown below inTable 1.

TABLE 1 PUCCH length (Number OFDM of Number Format symbols) of bitsUsage example Other 0 1-2  ≤2 HARQ, SR Sequence selection 1 4-14 ≤2HARQ, [SR] Sequence modulation (BPSK, QPSK) 2 1-2  >2 HARQ, CSI, [SR][CP-OFDM] 3 4-14 [>N] HARQ, CSI, [SR] DFT-s-OFDM (no UE multiplexing) 44-14 >2, [≤N] HARQ, CSI, [SR] DFT-s-OFDM (Pre DFT OCC)

<Uplink (UL) Signal/Channel Multiplexing>

In NR, uplink (UL) signal/channel multiplexing may have the followingcharacteristics.

For the multiplexing of the PUCCH and PUSCH, the following techniquesmay be supported. For example, a time division multiplexing (TDM)technique (or scheme) may be supported between a short PUCCH (e.g.,formats 0/2) and a PUSCH. Additionally, for example, a frequencydivision multiplexing (FDM) technique (or scheme) may be supportedbetween a short PUCCH (e.g., formats 0/2) corresponding to a slot havinga short uplink part (UL-part) of a UE (other than Re-15) and a PUSCH.

For the multiplexing of the PUCCH and PUSCH, the following techniquesmay be supported. For example, a TDM/FDM technique (or scheme) may besupported between a short PUCCH (e.g., formats 0/2) and a long PUCCH(e.g., formats 1/3/4). Additionally, for example, a TDM technique (orscheme) may be supported between short PUCCHs (e.g., formats 0/2) withinthe same slot of a single UE. Furthermore, for example, a TDM technique(or scheme) may be supported between a short PUCCH (e.g., formats 0/2)and a long PUCCH (e.g., formats 1/3/4) within the same slot of a singleUE.

As described above, FIG. 10 shows an example of a multiplexing schemewithin a single slot in the NR.

Referring to FIG. 10, FIG. 10 shows an example wherein the long-PUCCH ispositioned in different frequency bands from symbol #3 to symbol #7 andfrom symbol #8 to symbol #11 in an uplink (UL) region within a singleslot. And, FIG. 10 also shown an example wherein each of the shortPUCCHs is respectively positioned in symbol #12 and symbol #13. Morespecifically, FIG. 10 shows an example wherein TDM is performed betweenshort PUCCHs, and wherein TDM/FDM is performed between a short PUCCH anda long PUCCH.

<Control Information Modulation and Coding Scheme (MCS) Offset>

In NR, semi-persistent and dynamic indication may both be supported fora beta-offset. Additionally, for a dynamic beta-offset indication, aplurality of beta-offset value sets may be configured by RRC signaling,and a UL grant may dynamically indicate an index for a set. Herein, eachset may include a plurality of entries, and each entry may correspond toeach UCI type (including a case where a two-part CSI can be applied).

<UCI Mapping>

For slot-based scheduling, a PUSCH may be processed with rate-matchingfor an HARQ-ACK exceeding 2 bits, and the PUSCH may be processed withpuncturing for an HARQ-ACK less than or equal to 2 bits.

In NR, a case where downlink (DL) assignment is later than a UL grant,which is mapped to a same time instance for an HARQ-ACK transmissionwithin the PUSCH, may not be supported.

Additionally, UCI (e.g., HARQ-ACK or CSI), which is piggy-backed withinthe PUSCH, may be mapped to REs that are dispersed and distributedthroughout RBs being assigned to the PUSCH.

Regardless of HARQ-ACK puncturing or PUSCH rate-matching, the same REmapping rule may be applied to the HARQ-ACK piggy-back within the PUSCH.For example, localized mapping or distributed mapping may be performedadjacent to the DM-RS within the time domain.

<Scheduling/HARQ Timing>

In NR, scheduling/HARQ timing may have the following characteristics.

For dynamic indication of scheduling/HARQ timing, slot timing between Aand B may be indicated by a field within the DCI from a set of values,and the set of values may be configured by UE-specific RRC signaling.Herein, all Rel. 15 UEs may support a minimum value of K0, such as 0.

Meanwhile, K0 to K2 for A and B may be defined as shown below in Table2.

TABLE 2 A B K0 Downlink scheduling DCI Corresponding downlink datatransmission K1 Downlink data reception Corresponding HARQ-ACK K2 Uplinkscheduling DCI Corresponding uplink data transmission

A UE processing time capability may be indicated in symbols (N1, N2).Herein, N1 may indicate a number of OFDM symbols that are needed for theprocessing of the UE starting from an end of an NR-PDSCH reception to anearliest possible start of its respective ACK/NACK transmission in theviewpoint of the UE. And, N2 may indicate a number of OFDM symbols thatare needed for the processing of the UE starting from an end of anNR-PDCCH including a UL grant reception to an earliest possible start ofits respective NR-PUSCH transmission in the viewpoint of the UE.

Minimum values of (K1, K2) of the UE may be determined based on (N1,N2), a timing advance (TA) value, UE DL/UL switching, and so on.

Meanwhile, in the NR, two types of UE processing time capabilities maybe defined for slot based scheduling corresponding to a case of a non-CAusing a single numerology for at least PDCCH, PDSCH, and PUSCH.

For example, for the given settings and numerology, the UE may indicateonly one capability for N1 (or N2) based on an entry of thecorresponding N1 (or N2) from the two following tables (Table 3, Table4).

Capability #1 (Table 3): UE Processing Time Capability

TABLE 3 HARQ 15 30 60 120 timing KHz KHz KHz KHz Settings parameterUnits SCS SCS SCS SCS Front-loaded N1 Symbols [8] [10] [14] [14-21] DMRSonly Front-loaded + N1 Symbols [13]  [13] [17] [21] additional DMRSFrequency- N2 Symbols [9] [11] [17] [31] first RE- mapping

Capability #2 (Table 4): Active UE Processing Time Capability

TABLE 4 HARQ timing Setup parameter Units 15 KHz SCS 30 KHz SCSFront-loaded N1 Symbols [2.5-4] [2.5-6] DMRS only Front-loaded + N1Symbols [12] [12] additional DMRS Frequency-first N2 Symbols [2.5-6][2.5-6] RE-mapping

For mixed numerologies and scheduling/HARQ timing, when the numerologiesbetween a PDCCH and a transmission being scheduled by the PDCCH aredifferent from one another, for K0 or K2, a time granularity indicatedby the DCI may be based on the scheduled transmission.

HARQ-ACK transmission being associated with a plurality of DL elementcarriers operating based on the same or different numerology may besupported. A time granularity indicated by the DCI scheduling the PDSCHmay be based on the numerology of a PUCCH transmission.

<Code Block Group (CBG) Based (Re-)Transmission>

Synchronization: A partial transport block (TB) retransmission mayderive an efficient usage of resource. The retransmission unit maycorrespond to a code block group (CBG). However, when this method isused, HARQ-ACK feedback bits and DCI overhead may be increased.

Code block group (CBG) configuration: The UE may be semi-persistentlyconfigured, so as to be capable of performing CBG based retransmissionvia RRC signaling. A maximum value N of a CBG per TB may be set up byRRC signaling. In case of a single codeword (CW), the maximum value ofthe CBG per TB that can be set up may be equal to 8. In case of multipleCWs, the maximum value of the CBG per TB that can be set up may be equalto 4, and the set up maximum value of the CBG per TB may be the same ineach TB.

At least in case of a single CW, the number of CBGs in a TB may be equalto min(C, N), and, herein, C may indicate a number of CBs within the TB.Among a total of M number of CBGs, a first Mod(C, M) CBG may include aceil(C/M) CB per CBG. The remaining M-Mod(C, M) CBG may include afloor(C/M) CB per CBG.

In relation with the DCI, CBG transmission information (CBGTI) and CBGflushing out information (CBGFI) may be adopted. CBGTI: A CBG may be(re-)transmitted, and this may correspond to N bits of the CBGTI, whichis configured by RRC. CBGFI: The CBG may be processed different forsoft-buffer/HARQ combining, and this may correspond to another 1 bit (incase of at least a single CW) for the CBGFI.

For the downlink data, the CBGTI and the CBGFI may be included in thesame DCI. In Mode 1, the DCI may include the CBGTI. In Mode 2, the DCImay include both the CBGTI and the CBGFI.

For the uplink data, the CBGTI may be configured to be included in theDCI. In Mode 1, the DCI may include the CBGTI.

In the HARQ-ACK feedback, for an initial transmission and aretransmission, the same set of CB(s) may exist in each CBG of the TB.When a CBG based retransmission is configured, the UE may use a TB-levelHARQ-ACK feedback for a PDSCH, which is scheduled by the PDCCH usingfallback DCI, at least in a case where HARQ-ACK multiplexing is notperformed. This may indicate that the fallback DCI does not supportCBG-level HARQ-ACK feedback.

For a semi-persistent HARQ-ACK codebook, the HARQ-ACK codebook mayinclude HARQ-ACKs corresponding to all of the configured CBGs (includingCBGs that are not scheduled). If the same CBG is successfully decoded,an ACK may be reported for the corresponding CBG. If a TB CRC is notpassed while a CB CRC check is passed for all CBs, a NACK may bereported for all CBGs. If a number of CBs for the TB is smaller than apre-determined maximum number of CBGs, a NACK may be mapped to a blankCBG index.

Hereinafter, the present invention will be described in detail.

As described above, in the NR, discussions are being made based on acommunication system design considering services/terminals (or UEs) thatare sensitive to reliability and latency. And, additionally, discussionsare also being made on an introduction of a next generation radio accesstechnology considering Ultra-Reliable and Low Latency Communication(URLLC), and so on.

Meanwhile, retransmission of data through a hybrid automatic repeatrequest (HARQ) process may also be performed in the NR. However, in theNR, by defining a channel that spreads in system bandwidth units,discussions are being made on a more efficient usage method for usingsymbols being consumed. And, accordingly, discussions are also beingmade on a method for performing an HARQ process without adopting aphysical HARQ indicator channel (PHICH) in the related art LTE.

Accordingly, the present invention uses downlink control information(DCI) as a retransmission indicator so as to provide a method performedby a terminal (or user equipment (UE)) resending (or retransmitting)data.

For example, the methods proposed below respectively propose methods forefficiently triggering retransmission for a plurality of (uplink(UL)/downlink (DL)) data (synchronously). Herein, for example, (part of)the proposed methods of the present invention may be extendedly appliedfor uplink (UL) communication (and/or downlink (DL) communication)and/or “non-adaptive retransmission (NA-RETX)” (For example, theretransmission operation may be performed based on an HARQ feedbackchannel being related to whether or not data reception is successful.More specifically, it may be understood that, instead of (additionally)transmitting a retransmission-related scheduling grant, schedulinginformation being related to the initial transmission is also (fully orpartly) used for the retransmission.) (and/or “adaptive retransmission(A-RETX)” (For example, the retransmission operation may be performedbased on a retransmission-related scheduling grant (and/or an HARQfeedback channel being related to whether or not data reception issuccessful). More specifically, it may be understood that the(additionally transmitted) retransmission-related scheduling grant isused for the retransmission).). Herein, for example, “non-adaptiveretransmission (NA-RETX)” wording used in the present invention may be(extendedly or interchangeably) understood (or interpreted as) “adaptiveretransmission (A-RETX)” wording. Additionally, “retransmissionindication” wording used in the present invention may be extendedlyunderstood (or interpreted as) a “new transport block (TB) indication”.

FIG. 11 is a flow chart showing a method for retransmitting data of a UEaccording to an exemplary embodiment of the present invention.

According to FIG. 11, a user equipment (UE) receives downlink controlinformation (DCI) from a network (S1110). At this point, the DCIincludes an acknowledgement/not-acknowledgement (ACK/NACK) field or aretransmission indication field.

Thereafter, the UE retransmits data based on the DCI (S1120). Herein,for example, the retransmission may correspond to non-adaptiveretransmission. Additionally, for example, the DCI may indicateretransmission per HARQ process ID. Additionally, for example, the DCImay indicate retransmission per subframe within a subframe window.Additionally, for example, in case a counter field indicating ascheduling index within the uplink (UL) grant is defined, the DCI maysignal a last counter value. Additionally, for example, in case apolling on/off field is defined within the UL grant, and, when a pollingon UL grant is received in an N^(th) subframe, an UL grant being theindication target of the DCI that is received after a time point of theN^(th) subframe may correspond to an uplink grant that is receivedduring a duration starting from a reception point of a nearest pollingon uplink grant before the N^(th) subframe to an (N−1)^(th) subframe.Additionally, for example, the DCI may correspond to a UE-specific DCIor a UE-common DCI. Additionally, for example, the DCI may include atleast any one of a non-adaptive retransmission on/off field, anon-adaptive retransmission timing field, a redundancy version (RV)field, and an aperiodic channel state information (CSI) transmissionrequest field. Additionally, for example, a radio network temporaryidentifier (RNTI) value that is related to the detection of the DCI maybe independently signaled. Additionally, for example, atransmission-related parameter within a search space for the DCI may bepredetermined in advance. Additionally, for example, in case the UEreceives both the DCI and uplink grant for the same HARQ process ID,retransmission may be performed in accordance with the uplink grant.Additionally, for example, an HARQ ACK transmission timing field may beconfigured per HARQ process ID within the DCI. Furthermore, for example,an acknowledgement/not-acknowledgement resource indicator (ARI) fieldmay be configured per HARQ process ID within the DCI.

Hereinafter, a detailed example of a method for retransmitting data ofthe user equipment (UE) according to FIG. 11 will be described indetail.

As described above, the UE receives the downlink control information(DCI) from a network and retransmits data based on the DCI. Herein, theDCI may include an acknowledgement/not-acknowledgement (ACK/NACK) field.In other words, in the related art 3GPP LTE, although the UE hasreceived an ACK/NACK over a PHICH, instead of doing so, in the presentinvention, the UE receives DCI including an ACK/NACK field and thenperforms an HARQ process for the data based on the received DCI.Additionally, the re-transmission may correspond to a non-adaptiveretransmission. Hereinafter, a detailed example of this procedure willbe described below.

[Proposed Method #1] For example, when NA-RETX for a plurality of(uplink) data are (synchronously) triggered by a single (pre-defined)indicator (e.g., “DCI”) (NA-RETXINDI), (part of) the following rules maybe applied.

As described above, the DCI may indicate retransmission per hybridautomatic repeat request process identifier (HARQ process ID).Hereinafter, a detailed example of this procedure will be describedbelow.

(Example #1-1-1) For example, the NA-RETX may be indicated per HARQPROCESS (GROUP) ID.

Herein, for example, in case the corresponding rule is applied, a field(or fields) for NA-RETX indication per HARQ PROCESS (GROUP) ID withinthe NA-RETXINDI may be defined.

Herein, for example, interconnected HARQ PROCESS (GROUP) IDs per field(index) may be configured in accordance with a pre-defined rule (e.g., astructure of (implicitly) mapping a relatively low (or high) HARQPROCESS (GROUP) ID to a relatively low field index) and/or may besignaled (e.g., RRC SIGNALING) (from the base station).

As described above, the DCI may indicate retransmission per subframewithin a subframe window. Additionally, in case a counter fieldindicating a scheduling index within the uplink (UL) grant is defined,the DCI may signal a last counter value. In other words, for example,when the counter value of the UL grant is equal to 5, a number of ULgrants corresponding to the counter value may become targets ofretransmission triggering. Herein, whether or not retransmission of theuplink data is actually required in the network is not considered.

Additionally, when the DCI is received, the counter value may beinitialized. In other words, in case of a transmission that is based onthe above-described counter value, retransmission may be excessivelyrequired for the data being actually received by the network. Herein,excessive retransmission, as shown in the above-described example, maybe prevented by using the DCI that initialized the counter value.

Additionally, in case a polling on/off field is defined within the ULgrant, and, when a polling on UL grant is received in an N^(th)subframe, an UL grant being the indication target of the DCI that isreceived after a time point of the N^(th) subframe may correspond to anuplink grant that is received during a duration starting from areception point of a nearest polling on uplink grant before the N^(th)subframe to an (N−1)^(th) subframe. In other words, by adjusting aninterval between two polling on UL grants that are received by the UE,the data retransmission duration may be adjusted. Hereinafter, adetailed example of this procedure will be described below.

(Example #1-1-2) For example, the NA-RETX may be indicated per subframe(group) within a subframe window (RETX_SFWIN).

Herein, for example, in case the corresponding rule is applied, a field(or fields) for NA-RETX indication per subframe (group) index (within aRETX_SFWIN) within the NA-RETXINDI may be defined.

Herein, for example, (in the present invention) a “subframe (group)index” wording may also be interpreted as a finally derived index afterperforming re-indexing if the subframes included in the RETX_SFWIN.

Herein, for example, interconnected subframe (group) indexes per field(index) may be configured in accordance with a pre-defined rule (e.g., astructure of (implicitly) mapping a relatively low (or high) subframe(group) index to a relatively low field index) and/or may be signaled(e.g., RRC SIGNALING) from the (base station).

Herein, for example, a NA-RETX indication target subframe window size(RETX_SFWINSIZE) may be signaled (e.g., RRC SIGNALING) from the (basestation) and/or may be signaled via (field defined for the correspondingpurpose within) the NA-RETXINDI (or a newly defined indicator).

As another example, in case a counter (SCH_CNT) field indicating ascheduling index within the UL GRANT (e.g., a function similar to the(conventional) “DOWNLINK ASSIGNMENT INDEX (DAI)” field) is defined, alast counter value (LAST_CVAL) (related to retransmission triggering)may be signaled (through a pre-defined field) within the NA-RETXINDI(e.g., (in this case) the UL GRANT of “0˜(LAST_CVAL−1)” counter valuesbecomes a NA-RETX (synchronous) triggering target).

Herein, for example, a SCH_CNT value may be configured to be initializedafter a NA-RETXINDI transmission/reception.

Herein, for example, by doing so, signaling of (A) dynamicshift(/indication) of RETX_SFWIN (and/or RETX_SFWINSIZE) and/or (B)information on a number of (total) HARQ PROCESS (GROUP) IDs (or subframe(groups)) in which presence or absence of the NA-RETX is to be indicatedvia the (corresponding) NA-RETXINDI can be performed.

As another example, in case a “POLLING ON/OFF” field (e.g., “1=ON”,“0=OFF”) is defined within the UL GRANT, if “UL GRANT W/POLLINGON/OFF=1” is received at a SF#N time point, (A) the UL GRANT being theNA-RETX (presence or absence) indication target of the NA-RETXINDI,which is received (earliest) after a time point including the SF#N (orSF#(N+1)) time point, is defined(/assumed) as (all) UL GRANT beingreceived during a duration starting from a “UL GRANT W/POLLING ON/OFF=1”reception point (SF#K), which is positioned at a nearest point beforethe SF#N time point, to a SF#(N−1) time point (or a duration startingfrom a SF#(K+1) time point to a SF#N time point) and/or (B) theRETX_SFWIN of the NA-RETXINDI, which is received (earliest) after a timepoint including the SF#N (or SF#(N+1)) time point becomes a durationstarting from the SF#K time point to the SF#(N−1) time point (or aduration starting from the SF#(K+1) time point to the SF#N time point).

FIG. 12 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

According to FIG. 12, for example, 6 HARQ process IDs may exist, such asHARQ process IDs #0, #1, #2, #3, #4, and #5. Herein, the UE may receivethe DCI in subframe N. Herein, for example, data retransmission forsubframes K, K+1, K+2, K+3, K+4, and K+5 via DCI may be considered.Herein, HARQ process IDs #0 to #5 may be serially configured tocorrespond to subframes K to K+5. Herein, for example, when the UEreceives a bit sequence of 001010 through the received DCI, the UE mayperform retransmission for HARQ process IDs #2 and #4.

Additionally, herein, for example, a duration starting from subframes Kto K+5 may be configured as a subframe window via the received DCI, andretransmission per subframe within the window may be indicated via thereceived DCI.

FIG. 13 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

According to FIG. 13, the UE may receive the DCI in the N^(th) subframe.Herein, for example, scheduling may be performed by the uplink (UL)grant for the K^(th) subframe to the (K+4)^(th) subframe. Herein, incase a counter field indicating a scheduling index within the uplink(UL) grant is defined, counter values of 0, 1, . . . , 5 may berespectively assigned to subframe K to subframe K+4. Herein, bysignaling a last counter value from the received DCI, retransmission maybe performed for all of the data being transmitted from the K^(th)subframe to the (K+4)^(th) subframe.

Herein, whether or not the retransmitted data is actually received bythe network is not a subject for consideration. Herein, for example, thecounter value is initialized after the DCI reception, and, by adjustingthe transmission time point of the DCI, excessive data retransmissionmay be prevented.

FIG. 14 shows a general view of a data retransmission method accordingto an exemplary embodiment of the present invention.

According to FIG. 14, the UE receives a polling on UL grant from theN^(th) subframe. Herein, the subframe that receives the nearest pollingon uplink grant before the N^(th) subframe may correspond to a K^(th)subframe (wherein K<N). Additionally, herein, the subframe that receivesthe nearest DCI after the N^(th) subframe may correspond to a P^(th)subframe (wherein P>N). Herein, the UL grant that corresponds to aretransmission target being indicated by the DCI, which is received bythe P^(th) subframe, may correspond to a UL grant being received duringa duration starting from a time point of the K^(th) subframe to a timepoint of the (N−1)^(th) subframe (wherein N−1>K).

As described above, the DCI may correspond to a UE-specific DCI or aUE-common DCI. Hereinafter, a detailed example of this procedure will bedescribed below.

(Example #1-2) For example, the NA-RETXINDI may be configured(/defined)to have a “UE-SPECIFIC DCI” structure.

Herein, for example, a payload size of the corresponding NA-RETXINDI maybe configured(/defined) to be the same as the (general) UL GRANT (e.g.,DCI FORMAT 0(/4)) (for example, (in this case,) whether theconfiguration corresponds to the (general) UL GRANT or the NA-RETXINDIis determined based on a “FLAG FIELD”, which is pre-defined (within theNA-RETXINDI)) and/or the payload size may be independentlyconfigured(/defined).

For example, the NA-RETXINDI may be configured(/defined) to have a “UE(GROUP)-COMMON DCI” structure. Herein, for example, in case of applyingthe corresponding rule, NA-RETXINDI, which is similar to the(conventional) “DCI FORMAT 3/3A”, may independently trigger a NA-RETXper UE, in state where different MULTI-BITs are assigned to multiple UEswithin a single DCI.

As described above, the DCI may include at least any one of anon-adaptive retransmission on/off field, a non-adaptive retransmissiontiming field, a redundancy version (RV) field, and an aperiodic channelstate information (CSI) transmission request field. Hereinafter, adetailed example of this procedure will be described below.

(Example #1-3) For example, (part of) the following fields may bedefined (per UE) within the NA-RETXINDI.

Herein, for example, according to the number of data transmissions (ofdifferent HARQ PROCESS (GROUP) IDs) that are actually performed in theRETX_SFWIN, a (total) number of specific fields that are to be definedwithin the NA-RETXINDI may be changed. (For example, in case “N” numberof actual data transmissions (of different HARQ PROCESS (GROUP) IDs) areperformed within the RETX_SFWIN, (a total of) “N” number of “NA-RETXON/OFF” fields may be defined(/configured) within the NA-RETXINDI.)

-   -   “NA-RETX ON/OFF (e.g., operationally equivalent to PHICH        A/N(acknowledgement/not-acknowledgement))” field

Herein, for example, “1-BIT” may be assigned per HARQ PROCESS (GROUP) ID(or subframe (group)).

-   -   “NA-RETX TIMING” field

Herein, for example, (A) a (separate) “NA-RETX TIMING” field may beconfigured(/defined) per HARQ PROCESS (GROUP) ID (or subframe (group))and/or (B) only one (main) “NA-RETX TIMING” field may beconfigured(/defined), and, based on the indicated (NA-RETX) timing, theNR-RETX may be serially performed (within a time domain) in anincreasing (or decreasing) format of the HARQ PROCESS (GROUP) ID (orsubframe (group) index).

As another example, a (semi-persistently) fixed (NA-RETX) timing that isconfigured(/signaled (e.g., via RRC SIGNALING)) in advance may beapplied, without any separate “NA-RETX TIMING” fieldconfiguration(/definition) within the NA-RETXINDI.

Herein, for example, the corresponding (NA-RETX) timing may bedifferently (or identically) designated per HARQ PROCESS (GROUP) ID (orsubframe (group) index).

-   -   “REDUNDANCY VERSION (RV)” field

Herein, for example, (A) a (separate) “RV” field may beconfigured(/defined) per HARQ PROCESS (GROUP) ID (or subframe (group))and/or (B) only one (main) “RV” field may be configured(/defined), and,the indicated RV value may be commonly applied to all HARQ PROCESS(GROUP) ID (or subframe) related NA-RETX.

As another example, a (semi-persistently) fixed RV value that isconfigured(/signaled (e.g., via RRC SIGNALING)) in advance may beapplied, without any separate “RV” field configuration(/definition)within the NA-RETXINDI.

Herein, for example, the corresponding RV value may be differently (oridentically) designated per HARQ PROCESS (GROUP) ID (or subframe (group)index).

-   -   “APERIODIC CSI(/SRS) TRANSMISSION REQUEST” field

Herein, for example, in case the APERIODIC CSI(/SRS) transmission isrequested, (A) all NA-RETX(S) (being (synchronously) triggered to thecorresponding NA-RETXINDI) may be configured to apply the APERIODICCSI(/SRS) transmission and/or (B) specific (or part of) NA-RETXinformation to which the APERIODIC CSI(/SRS) transmission is to beapplied may be configured to be signaled through (fields defined for thecorresponding purpose within) the NA-RETXINDI (or a newly definedindicator) and/or (C) the APERIODIC CSI(/SRS) transmission may beapplied only to a (single) specific NA-RETX (e.g., first (or last)NA-RETX) that is pre-configured(/signaled (e.g., via RRC SIGNALING)) inadvance.

-   -   “(NA-RETX related) HARQ PROCESS (GROUP) ID (or SUBFRAME (GROUP)        INDEX)” field    -   “NUMBER OF TOTAL HARQ PROCESS (GROUP) ID (or SUBFRAME (GROUP))        INTENDED TO INDICATE (PERFORMANCE OR NON-PERFORMANCE OF) NA-RETX        (WITHIN NA-RETXINDI)” field    -   “(NA-RETX related) DM-RS CYCLIC SHIFT (CS) INDEX” field (and/or        “(NA-RETX related) TRANSMISSION POWER COMMAND” field and/or        “(NA-RETX related) (ANALOG) BEAM RELATED INFORMATION” field        and/or “(NA-RETX related) CARRIER (or (SUB)BAND) (INDEX)        INDICATOR” field (and/or “(retransmission related) MCS” field        and/or “(retransmission) related (frequency) RESOURCE        ALLOCATION” field))

As described above, a radio network temporary identifier (RNTI) valuethat is related to the detection of the DCI may be independentlysignaled. Additionally, a transmission-related parameter within a searchspace for the DCI may be predetermined in advance. Hereinafter, adetailed example of this procedure will be described below.

(Example #1-4) For example, a NA-RETXINDI (blind) detection related RNTIvalue may be signaled independently (or differently) (from a (C−)RNTIvalue (being used for the conventional DCI (having the same payloadsize) (e.g., DCI FORMAT 0(/4))). For example, a NA-RETXINDItransmission(/detection) related parameter (e.g., (E)PDCCH CANDIDATELOCATION, (lowest) AGGREGATION LEVEL (AL), number of blind decoding perAL, etc.) within a (UE-SPECIFIC or (UE GROUP) COMMON) SEARCH SPACE (SS)may be configured(/signaled (e.g., via RRC SIGNALING)) in advance.

Additionally, in case the UE receives both the DCI and uplink grant forthe same HARQ process ID, retransmission may be performed in accordancewith the uplink grant. Hereinafter, a detailed example of this procedurewill be described below.

(Example #1-5) For example, in case the UE receives all of the(above-described) NA-RETXIND (indicating retransmission) and (general)(A-RETX) UL GRANT (e.g., DCI FORMAT 0(/4)), for the same HARQ PROCESS(GROUP) ID (or subframe (group) index), the UE may be configured toperform retransmission in accordance with the (A-RETX) UL GRANT (orNA-RETXINDI).

Herein, for example, in case the corresponding rule is applied, ascompared to the NA-RETXINDI, the (A-RETX) UL GRANT may be interpreted tohave a relatively higher (or lower) priority level (in light ofretransmission indication).

As described above, an HARQ acknowledgement (ACK) transmission timingfield may be configured per HARQ process ID within the DCI. Hereinafter,a detailed example of this procedure will be described below.

[Proposed Method #2] For example, in case (part of) the above-describedproposed methods are applied to the NA-RETX (and/or A-RETX) for aplurality of downlink data, (part of) the following rules may be(additionally) applied.

(Example #2-1) For example, retransmission related HARQ-ACK transmissiontiming (HQTX_TIMING) may be determined according to (part of) thefollowing rules.

(Rule #2-1-1) For example, within the NA-RETXINDI, (A) a (separate)“HQTX_TIMING” field may be configured(/defined) per HARQ PROCESS (GROUP)ID (or subframe (group)) and/or (B) only one (main) “HQTX_TIMING” fieldmay be configured(/defined), and, based on the indicated HARQ-ACKtransmission timing, the HARQ-ACK transmission may be serially performed(within a time domain) in an increasing (or decreasing) format of theHARQ PROCESS (GROUP) ID (or subframe (group) index) and/or (c)“AGGREGATION” may be performed on the indicated the HARQ-ACKtransmission timing and the HARQ-ACK corresponding to all HARQ PROCESS(GROUP) ID (or subframe (group) index) (being (synchronously)(retransmission) triggered to the corresponding NA-RETXINDI)corresponding to all HARQ PROCESS (GROUP) ID (or subframe (group)index), and, then, the aggregation result may be transmitted.

As another example, a (semi-persistently) fixed HARQ-ACK transmissiontiming that is configured(/signaled (e.g., via RRC SIGNALING)) inadvance may be applied, without any separate “HQTX_TIMING” fieldconfiguration(/definition) within the NA-RETXINDI. Herein, for example,the corresponding HARQ-ACK transmission timing may be differently (oridentically) designated per HARQ PROCESS (GROUP) ID (or subframe (group)index).

As described above, an acknowledgement/not-acknowledgement (A/N)resource indicator (ARI) field may be configured per HARQ process IDwithin the DCI, and a physical uplink control channel (PUCCH) resourcemay be assigned based on the ARI. Hereinafter, a detailed example ofthis procedure will be described below.

(Example #2-2) For example, retransmission related “PUCCH RESOURCE(PUCCH_RSC)” may be determined according to (part of) the followingrules.

(Rule #2-2-1) For example, within the NA-RETXINDI, (A) a (separate) “A/NRESOURCE INDICATOR (ARI)” field may be configured(/defined) per HARQPROCESS (GROUP) ID (or subframe (group)) and/or (B) only one (main)“ARI” field may be configured(/defined), and, the PUCCH_RSCcorresponding to indicated ARI may be commonly assigned to all HARQPROCESS (GROUP) ID (or subframe (group) index) (being (synchronously)(retransmission) triggered to the corresponding NA-RETXINDI).

As another example, a (semi-persistently) fixed PUCCH_RSC that isconfigured(/signaled (e.g., via RRC SIGNALING)) in advance may beassigned, without any separate “ARI” field configuration(/definition)within the NA-RETXINDI.

Herein, for example, the corresponding PUCCH_RSC may be differently (oridentically) designated per HARQ PROCESS (GROUP) ID (or subframe (group)index).

FIG. 15 shows a detailed example of applying the method of FIG. 11.

According to FIG. 15, a user equipment (UE) transmits uplink data to abase station (S1510).

Afterwards, the base station measures whether to receive the uplink dataor not (S1520).

Subsequently, the base station transmits DCI, which includes anacknowledgement (ACK) field that is based on the measurement result, tothe UE (S1530).

Thereafter, the UE retransmits data based on the DCI (S1540). Herein,for example, the retransmission may correspond to non-adaptiveretransmission. Additionally, for example, the DCI may indicateretransmission per HARQ process ID. Additionally, for example, the DCImay indicate retransmission per subframe within a subframe window.Additionally, for example, in case a counter field indicating ascheduling index within the uplink (UL) grant is defined, the DCI maysignal a last counter value. Additionally, for example, in case apolling on/off field is defined within the UL grant, and, when a pollingon UL grant is received in an N^(th) subframe, an UL grant being theindication target of the DCI that is received after a time point of theN^(th) subframe may correspond to an uplink grant that is receivedduring a duration starting from a reception point of a nearest pollingon uplink grant before the N^(th) subframe to an (N−1)^(th) subframe.Additionally, for example, the DCI may correspond to a UE-specific DCIor a UE-common DCI. Additionally, for example, the DCI may include atleast any one of a non-adaptive retransmission on/off field, anon-adaptive retransmission timing field, a redundancy version (RV)field, and an aperiodic channel state information (CSI) transmissionrequest field. Additionally, for example, a radio network temporaryidentifier (RNTI) value that is related to the detection of the DCI maybe independently signaled. Additionally, for example, atransmission-related parameter within a search space for the DCI may bepredetermined in advance. Additionally, for example, in case the UEreceives both the DCI and uplink grant for the same HARQ process ID,retransmission may be performed in accordance with the uplink grant.Additionally, for example, an HARQ ACK transmission timing field may beconfigured per HARQ process ID within the DCI. Furthermore, for example,an acknowledgement/not-acknowledgement resource indicator (ARI) fieldmay be configured per HARQ process ID within the DCI.

Herein, since the detailed example of retransmitting data by the UE isthe same as the description presented above, a detailed description ofthe same will be omitted for simplicity.

FIG. 16 is a block diagram illustrating a communication device in whichembodiments of the present invention are implemented.

Referring to FIG. 16, the BS 100 includes a processor 110, memory 120,and a Radio Frequency (RF) unit 130. The processor 110 implements theproposed functions, processes and/or methods. The memory 120 isconnected to the processor 110, and the memory stores various types ofinformation for driving the processor 110. The RF unit 130 is connectedto the processor 110, and the RF unit sends and/or receives radiosignals.

The user equipment (UE) 200 may include a processor 210, memory 220, anda RF unit 230. The processor 210 implements the proposed functions,processes and/or methods. For example, the processor 210 may receive theuplink communication related parameters set independently for eachanalog beam, and apply the parameters to perform the uplinkcommunication. Herein, when the uplink communication is performed usinga specific analog beam, the uplink communication related parameter setin the specific analog beam may be applied to the uplink communication.The memory 220 is connected to the processor 210, and the memory storesvarious types of information for driving the processor 210. The RF unit230 is connected to the processor 210, and the RF unit sends and/orreceives radio signals.

The processor 110, 210 may include Application-Specific IntegratedCircuits (ASICs), other chipsets, logic circuits, data processors and/orconverters for converting baseband signals and radio signals. The memory120, 220 may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit 130, 230 may include one or more antennas for sending and/orreceiving radio signals. When the embodiment is implemented in software,the above-described scheme may be implemented as a module (process,function, etc.) for performing the above function. The module may bestored in the memory 120, 220 and executed by the processor 110, 210.The memory 120, 220 may be placed inside or outside the processor 110,210 and connected to the processor 110, 210 using a variety ofwell-known means.

Since the examples of the above-described proposed methods may beincluded as one of the implementation methods of the present invention,it will be apparent that the corresponding example can be viewed (andunderstood) as one of the proposed methods. Additionally, although theproposed methods, which are described above, may be implementedindependently, the present invention may also be implemented to acombined (or integrated) structure of part of the proposed methods. Forexample, the scope of systems adopting the proposed methods of thepresent invention may be extended to systems other than the 3GPP LTEsystem.

The above-described exemplary embodiment included diverse examples. Itwill be apparent to anyone skilled in the art that a combination of allpossible examples of the present invention cannot be fully described,and it will also be apparent to anyone skilled in the art that the othercombinations may be derived from the detailed description of thespecification presented herein. Therefore, the scope of the presentinvention shall be understood and determined by combining the diverseexamples presented in the detailed description of the present invention,without departing from the scope and spirit of the present invention.

What is claimed is:
 1. A method for retransmitting data of a userequipment (UE) in a wireless communication system, comprising: receivingdownlink control information (DCI) from a network; and retransmittingdata based on the DCI, wherein the DCI includes anacknowledgement/not-acknowledgement (ACK/NACK) field.
 2. The method ofclaim 1, wherein the retransmission is a non-adaptive retransmission. 3.The method of claim 1, wherein the DCI informs retransmission per hybridautomatic repeat request process identifier (HARQ process ID).
 4. Themethod of claim 1, wherein the DCI informs retransmission per subframewithin a subframe window.
 5. The method of claim 1, wherein, in case acounter field informing a scheduling index within the uplink (UL) grantis defined, the DCI signals a last counter value.
 6. The method of claim5, wherein the counter value is initialized when the DCI is received. 7.The method of claim 1, wherein, in case a polling on/off field isdefined within the UL grant, and, when a polling on UL grant is receivedin an N^(th) subframe, an UL grant being a target of the DCI that isreceived after a time point of the N^(th) subframe is an uplink grantthat is received during a duration starting from a reception point of anearest polling on uplink grant before the N^(th) subframe to an(N−1)^(th) subframe.
 8. The method of claim 1, wherein the DCI is aUE-specific DCI or a UE-common DCI.
 9. The method of claim 1, whereinthe DCI includes at least any one of a non-adaptive retransmissionon/off field, a non-adaptive retransmission timing field, a redundancyversion (RV) field, and an aperiodic channel state information (CSI)transmission request field.
 10. The method of claim 1, wherein a radionetwork temporary identifier (RNTI) value being related to a detectionof the DCI is independently signaled.
 11. The method of claim 1, whereina transmission-related parameter within a search space for the DCI ispredetermined.
 12. The method of claim 1, wherein, in case the UEreceives both the DCI and uplink grant for a same HARQ process ID,retransmission is performed in accordance with the uplink grant.
 13. Themethod of claim 1, wherein an HARQ ACK transmission timing field isconfigured per HARQ process ID within the DCI.
 14. The method of claim1, wherein an acknowledgement/not-acknowledgement resource indicator(ARI) field is configured per HARQ process ID within the DCI.
 15. Acommunication device, comprising: a radio frequency (RF) unittransmitting and receiving radio signals; and a processor beingoperatively connected to the RF unit, wherein the processor isconfigured: to receive downlink control information (DCI) from anetwork, and to retransmit data based on the DCI, wherein the DCIincludes an acknowledgement/not-acknowledgement (ACK/NACK) field.